When we list the Matriarchs in prayers (such as the Amidah in the version including the matriarchs, or in the traditional blessing for one's daughters on Friday night), we say them in the order: Sarah, Rebekah, Rachel, Leah. Why is this? The patriarchs are generally listed in order of age, which seems like a natural order of precedence; and similarly, apart from Leah the matriarchs are listed in order of age.